This invention relates to a drive aggregate which is associated with a heat pump and which includes a compressor and an internal combustion engine driving the compressor. The engine and the compressor are combined into a structural unit by a common cylinder block which accommodates the compressor cylinders and the engine cylinders and which further has bearings for a common crankshaft, which may be a one-piece or a multi-piece component.
A drive aggregate of the above-outlined compact structure disclosed in U.S. patent application by Hofbauer et al, Ser. No. 84,137, filed Oct. 12th, 1979 has the advantage that a single cylinder block mass-manufactured for internal combustion engines may be used for both the engine and the compressor. It is, understandably, desirable to use, in the zone of the compressor, a cylinder head which too, is such a mass-manufactured component. Consequently, the use of a one-piece cylinder head for the entire heat pump drive aggregate is sought. These desiderata require, however, that the structure of the cylinder head for accommodating the valves of the internal combustion engine have no influence on the operation of the compressor because otherwise substantial subsequent alterations would be required in that zone of the cylinder head which covers the cylinder or the cylinders of the compressor.